This invention is in the field of seat belt buckles and other devices for restraining movement of a person. Seat belt buckles and their associated tongues are secured conventionally to belts fixedly mounted to the vehicle. Generally, a knurled bar is provided on the seat belt tongue and/or the seat belt buckle with the seat belt extending partially around the associated knurled bar. In order to tighten the seat belt buckle and tongue combination, the free end of the belt is pulled around the bar until the belt is tight. Over a period of time, the belt may slip relative to the knurled bar until the belt is loose. As a result, the person must then once again tighten the belt. This problem is particularly present and critical in heavy earth-moving vehicles which encounter rough terrain thereby applying a jerking motion to the occupant and seat belt buckle tongue combination. Disclosed herein is an anti-creep device for applying force to limit relative motion between the seat belt buckle-tongue combination and the seat belt web or belt.